300−P−9050075−E−01/11.06
ESV
2/17
Contents Page
1 General
description 3
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2 Advantages
3
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3 Application
3
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4 Technical
data
4
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5 Installation/startup
5
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5.1 Installation
information
5
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5.2 Adjustment
information
5
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6 Description
of
function
6
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7Port
designations
8
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8 Circuit
example
8
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9 Standard
design,
sizes
16/20
9
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9.1 Dimensions
9
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9.2 Performance
graphs
10
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9.3 Model
code
11
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10 Standard
design,
size
25
12
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10.1 Dimensions
12
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10.2 Performance
graphs
13
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10.3 Model
code
14
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11 Flat
design,
sizes
16/20
15
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11.1 Dimensions
15
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11.2 Performance
graphs
16
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11.3 Model
code
17
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300−P−9050075−E−01/11.06
ESV
3/17
1 General description
In accordance with standard EN 474−5 "Safety of earth−
moving machinery − Requirements for hydraulic exca-
vators", the excavator pipe−rupture valve, type ESV (Exca-
vator Safety Valve), prevents uncontrolled lowering of the
actuator in the event of a pipe− or hose−rupture. In addition,
it holds the actuator in its position without any leakage when
the main valve is centred. The valve also includes a second-
ary pressure−relief function, which protects the actuator
against overload.
2 Advantages
The inlet and actuator ports on the ESV excavator pipe−rup-
ture valve are standard SAE flanged ports, and the valve
can therefore be retrofitted to existing equipment without
any difficulty.
Thanks to its pilot−operated opening principle and outstand-
ing opening ratio, variations in load pressure − even right up
to the maximum − have no effect on the fine−control char-
acteristics and the hydraulic performance.
The ESV is set at the machine in a way that ensures that the
excavator pipe−rupture valve has no effect on the hydraulic
values that have already been set in the machine (pre−
opening principle). This means that excavators with and
without a lifting function can be equipped with the same
basic hydraulic system; the machines’ work cycles remain
unchanged.
The secondary pressure−relief valve that is employed is a
pressure−compensated design. Even when the main spool
valve is a closed−centre model and a secondary valve is
connected in series, no pressure summing occurs. The sec-
ondary pressure−relief valve in the excavator pipe−rupture
valve opens at exactly the opening pressure that has been
set. There is no need for a large−bore, external tank return
line.
3 Application
The leak−free excavator pipe−rupture valve is used wher-
ever so required by the standards EN 474, ISO 8643 and
DIN 24093 for excavators with a lifting device (e.g. a load
hook on the bucket). The actuators concerned are the lift
cylinder, the stick cylinder and the adjusting cylinder.
It is also possible to envisage other machine applications in
which a pipe−rupture on the actuators could produce dan-
gerous situations e.g. machines for materials handling and
demolition.
Attention: the excavator pipe−rupture valve may
only be used for the purpose for which it has been
designed!
300−P−9050075−E−01/11.06
ESV
4/17
4 Technical data
General characteristics Description, value, unit
Design proportionally−controlled seat valve, with initial hydraulic decompression
patented follower principle
Mounting method flange mounting, SAE 6000 psi
Mounting attitude unrestricted
Flow direction A → B free flow through check valve
B → A controlled flow
Weight standard design = 6.9 kg
flat design = 8.6 kg
Opening ratio 1:113 (seat area of pilot spool, to pilot−piston area)
Hydraulic characteristics Description, value, unit
Nominal sizes 16, 20
25
other sizes − consult Bucher Hydraulics
Nominal flow rate size 16 = 250 l/min
size 20 = 350 l/min
size 25 = 500 l/min
Pilot pressure range opening pressure min. 4 bar max. 9 bar (can be chosen)
full opening opening pressure + 14 bar + drain−oil back pressure
Operating pressure max. 420 bar
Secondary PRV − adjustment range min. 80 bar 420 bar (max. up to 460 bar also possible); settings are sealed
Operating fluid mineral oil to DIN 51524 and DIN 51525 (HL/ HLP)
other fluids − consult Bucher Hydraulics
Temperature range,
seal materials
Nitrile = −20 °C +90 °C
Viton = −20 °C +200 °C
Low (N7T40) = −50 °C +80 °C
Viscosity range min. 2.8 mm
2
/s (cSt) ... max. 1500 mm
2
/s (cSt)
recommended 10 mm
2
/s (cSt) 380 mm
2
/s (cSt)
Filtration NAS 1638 class 9, ß10 ≥ 75
ISO 4406 class 18/15
(valves do not have any internal filters)
Ports Description, value, unit
SAE to SAE J518 DEC87
Threads to DIN 3852, Parts 1 and 2
Fittings to ISO 8434−1
300−P−9050075−E−01/11.06
ESV
5/17
5 Installation/startup
5.1 Installation information
Attention: only trained and competent personnel
may carry out any work on the excavator pipe−rup-
ture valve!
The valve must not be opened without the manu-
facturer’s express permission!
Mounting bolts can be supplied as an optional extra and are
grade 12.9 to DIN 912, with "Geomet" surface treatment.
Before initial start−up, bleed all air from the hydraulic system.
Do not use any pipe fittings that have tapered threads.
Attention: before removing or disassembling the
valve, vent all hydraulic pressure from the system
− double check!
5.2 Adjustment information
Pressure−relief valves
Pressure−relief valves are factory−set to the pressure stipu-
lated by the customer and then sealed. The pressure is set
with flow Q = 0.75 l/min
S Clockwise → increases the pressure
S Counterclockwise → decreases the pressure
Change in pressure per turn
Basic setting Sizes 16/20 Size 25
>220 bar 80 bar 100 bar
p220 bar 40 bar 50 bar
Attention: the adjusting screw can be completely
unscrewed − it has no end−stop!
Important: if the adjustment seal is broken, the
warranty is null and void!
300−P−9050075−E−01/11.06
ESV
6/17
6 Description of function
Fig. 1 Sectional view
1 CV spring
2 Control spring
3 Control spring
4 Adjusting screw for secondary PRV
5 Poppet
7 Control spool
8 Pilot spool
9 Compensating pin
10 Pilot piston with compensating drilling
11 Precision washer
12 Stroke−limiting washer
13 Spring plate
14 Spring for secondary valve
A The secondary valve unit
B The load−control assembly
C The pilot control unit
Neutral position (load press. at B; A + X unpressurised)
In the neutral position, the excavator pipe−rupture valve has
zero leakage. The valve is held closed by the spring (1),
which acts on the pilot spool (8) and thus on the control
spool (7), and also by the load pressure, which acts on the
rear side of the pilot spool and the control spool.
The check−valve function (flow A B)
To raise the actuator, pump pressure is applied via port A to
the valve−seat area of the control spool (7) and causes the
control spool together with the pilot spool (8) to open, push-
ing against the light spring (1). When this check valve oper-
ates, the control spool moves in the opening direction but
the pilot spool, due to its small effective area, does not open.
The control function (flow B A)
1. Decompression
The pilot pressure at port X moves the pilot piston (10) in op-
position to the springs (2) and (3) and opens the pilot spool
(8). The load pressure behind the control spool now decays
as it escapes past the pilot spool to port A. The progressive
characteristic of the decompression phase ensures that the
actuator motion begins smoothly and without jerks.
300−P−9050075−E−01/11.06
ESV
7/17
2. Main opening
With further increase in the pilot pressure at X, the pilot spool
opens further and the reduced pressure behind the control
spool falls still more. The load pressure acting on the differ-
ential area of the control spool now pushes the spool off its
valve seat in the opening direction until the pressures of the
oilflows into, and out of, the control spool have changed
enough to produce a situation of force balance. The pilot
pressure acting on the pilot piston therefore controls the
open metering area of the control spool, and consequently
the flow rate from B → A. As the control spool opens, the
compensating pin (9) dictates that the opening action is
completely independent of any back−pressure in port A.
The opening point of each pipe−rupture valve is precisely
matched to the particular make/model of excavator and is
set to the required value on the test stand with precision
washers (11). Using stroke−limiting washers (12), the pilot
piston stroke can also be restricted. This in turn influences
the lowering speed.
During the lowering motion, and while the pilot pressure is
kept constant, the constantly changing geometry can result
in a steadily increasing load pressure. In this situation, from
approx. 100 bar load pressure the valve begins to function
like a compensated 2−way flow controller.
Function of the secondary pressure−relief valve
The secondary pressure−relief valve is connected directly to
actuator port B. When the pressure setting is reached, the
poppet (5) lifts and opens a connection to the return−line port
A. This path is sized for the full nominal flow rate. The poppet
is pressure balanced, so that forces resulting from back−
pressure in the return line cancel each other out. This
means that the opening point of the pressure−control valve
is independent of the back−pressure in the port A i.e. with a
closed−centre directional valve, no pressure summing oc-
curs with the necessary downstream pressure−relief valve.
The secondary pressure can be set at any desired level with
the adjusting screw (4). For basic settings p220 bar, the
second compression spring (13) and the spring plate (14)
are not fitted. This results in improved resolution at lower
pressure settings.
As an option, the valves can be provided with a separate ex-
ternal tank port.
Leakage−oil drain
The spring chambers of the pilot piston and the secondary
pressure−relief valve are drained to port L. This port should
be drained to tank with the least possible back−pressure.
Any tank back−pressure at port L has a 1:1 effect on the
opening values of both main functions.
Emergency−lowering feature
The standard ESV design does not have an emergency−
lowering feature.
Emergency lowering B L
In the flat ESV design, a mechanical emergency−lowering
screw is incorporated. The actuator is vented to port L
through a ø4 connecting drilling that is normally shut off.
When emergency lowering has been completed, the screw
must be screwed in again to restore the valve’s function!
Air−bleeding (optional)
The pilot piston includes a ø0.35 drilling for the permanent,
automatic bleeding of any air in the pilot circuit to drain port
L. There is a permanent flow of oil from X to L.
Air−bleeding X L (optional)
An air−bleed screw is also available for the flat valve design.
The pilot line is vented to port L through a connecting drilling
that is normally shut off. When emergency lowering has
been completed, the screw must be screwed in again to re-
store the valve’s function!
Accumulator port (optional)
As an option, the flat valve design can be provided with an
additional accumulator port. The port also has an M5 thread
for an orifice to provide the port with a minimum level of
protection.
300−P−9050075−E−01/11.06
ESV
8/17
7 Port designations
Port Description
B Actuator/load port
A, A1 Flow or return ports (the flat design has only one A port)
X Pilot port
L Drain port
E Port for balance pipe in parallel−cylinder applications; protected by a ø1 fixed orifice
MB Gauge port for the actuator/load pressure
S MB is not available on standard models in parallel applications; it is used as the E port
S Is separately drilled in the flat design
T (consult Bucher) Port for a possible external secondary PRV tank return line
S (consult Bucher) Special port for the actuator/load pressure (available as an option, and only for the flat design)
S Port for overload warning device
S Port for accumulator
S Optionally, can be fitted with an orifice
8 Circuit example
Fig. 2 Circuit example
300−P−9050075−E−01/11.06
ESV
9/17
9 Standard design, sizes 16/20
9.1 Dimensions
37.5
31.5
28
68
37.5
15 28
41.5
85
c
33142
130
143.5
b
a
213
75
L
X
A
E
B
A
A1
L
B
B
E
X
A
A1
E
B
A
X
L
ø1,0
A1
R
max
10
0.01 / 100 mm
1
Fig. 3 Dimensions of ESV 16−B−S / ESV 20−B−S
300−4−10012916
1 Required quality of the mating surface
Design Ports
O−ring
Port B
A, A1 B E (MB) L X
ESV 16−B−S SAE 3/4"
6000psi
SAE 3/4"
6000psi
G 1/4"
(GE 8 PSR)
EO GE 12 PLM−ED
(M18x1.5)
EO GE 12 PLM−ED
(M16x1.5)
3.53 x 24.99
ESV 20−B−S SAE 1"
6000psi
SAE 1"
6000psi
G 1/4"
(GE 8 PSR)
EO GE 12 PLM−ED
(M18x1.5)
EO GE 12 PLM−ED
(M16x1.5)
5.53 x 32.92
Design Dimensions [mm]
a b c
ESV 16−B M10 36.8 95
ESV 20−B M12 43 97
300−P−9050075−E−01/11.06
ESV
10/17
9.2 Performance graphs
∆p A to B = (Q)
Q [l/min]
pX [bar]
∆p B to A = (Q)
Q [l/min]
0 50 100 150 200 250 300 350
50
40
30
20
10
0
p [bar]
Pressure−relief valve, secondary PRV, Q = (Load)
(Example curve)
500
450
400
350
300
250
200
150
100
50
0
pB [bar]
050
*
*
100 150 200
Q [l/min]
* pressure setting
Opening pilot press. X from B to A, Q = (pX) at 33 bar load
pX [bar]
Q [l/min]
24
22
20
18
15
14
12
10
8
6
4
0
0
0
0
0
0
25
37.5
50
62.5
72.5
100
50
75
100
125
145
200
75
112.5
150
187.5
217.5
300
100
150
200
250
290
400
S100
S150
S200
S250
S290
S300
300−P−9050075−E−01/11.06
ESV
11/17
9.3 Model code
ESV
−−−−−−−−−−
−
B S SV
Nominal size
size 16 = 16
size 20 = 20
Version
B= B
Design
standard design = S
Seal material
Temperature range
Nitrile (standard) −20
o
C to +90
o
C= N
Nitrile (low temperature) −50
o
C to +80
o
C= T
Viton −20
o
C to +200
o
C= V
Mounting bolts
without mounting bolts = O
with surface−treated mounting bolts = D
Control spool
Q at approx.. 33 bar p B A Size 16 Size 20
100 l/min. = S100 = S100
150 l/min. = S150 = S150
200 l/min. = S200 = S200
250 l/min. = S250 = S250
290 l/min. = S290
300 l/min. = S300
Start of opening
Opening pressure ... bar = ... [bar]
Secondary pressure relief
Pressure relief from B =
Pressure setting
Pressure setting ... bar at approx. 0.75 l/min. = ... [bar]
Ports X, L, E
(standard) with fittings in X and L (E=VSTI) = V
with fittings in X, L and E = R
Inlet port
port A = A
portA1 = A1
port2A = 2A
Optional stroke−limiting
e.g. 1.2 mm of stroke−limiting (shims) = H12
Option (consult Bucher Hydraulics)
external tank port, G
3
/4 *= T
* only possible with type A inlet port
300−P−9050075−E−01/11.06
ESV
12/17
10 Standard design, size 25
10.1 Dimensions
42.25
18.5
114.5
119
E
B
X
L
MB
B
A
MB
E
X
A
48.5
88
39
46
4639
M14
54.5
168
153.5
175
35.5
40
92
248.5
A
A1
L
A1
E
B
A
X
L
ø1,0
MB
A1
R
max
10
0.01 / 100 mm
1
Fig. 4
300−4−10012913
1 Required quality of the mating surface
Design Ports
O−ring
Port B
A, A1 B E/MB L X
ESV 25−B SAE 1 1/4"
6000psi
SAE 1 1/4"
6000psi
G 1/4"
(GE 8 PSR)
GE 15 PLM−ED
(M22x1.5)
GE 12 PLM−ED
(M16x1.5)
3.53 x 37.69
300−P−9050075−E−01/11.06
ESV
13/17
10.2 Performance graphs
∆p A to B = (Q)
0
0
Q [l/min]
2
4
6
8
10
12
14
16
18
20
50 100 150 200 250 300 350 400 450 500
p [bar]
∆p B to A = (Q)
p [bar]
Q [l/min]
0
10
20
30
40
0 50 100 150 200 250 300 350 400 450 500
Pressure−relief valve, secondary PRV, Q = (Load)
(Example curve)
500
450
400
350
300
250
200
150
100
50
0
pB [bar]
0 100 200
*
*
300 400
Q [l/min]
* pressure setting
Example curve = setting
Opening pilot press. X from B to A, Q = (pX) at 33 bar load
pX [bar]
Q [l/min]
24
22
20
18
15
14
12
10
8
6
4
0
0
0
0
0
62.5
80
105
132.5
150
125
160
210
265
300
187.5
240
315
397.5
450
250
320
420
530
600
S250
S320
E420
E530
S500
300−P−9050075−E−01/11.06
ESV
14/17
10.3 Model code
ESV
−−−−−−−−−−
−
B S SV
Nominal size
size 25 = 25
Version
B= B
Design
standard design = S
Seal material
Temperature range
Nitrile (standard) −20
o
C to +90
o
C= N
Nitrile (low temperature) −50
o
C to +80
o
C= T
Viton −20
o
C to +200
o
C= V
Mounting bolts
without mounting bolts = O
with surface−treated mounting bolts = D
Control spool
Q at approx. 33 bar p B A Size 25
250 l/min. = S250
320 l/min. = S320
400 l/min. = S400
420 l/min. = (E420)
500 l/min. = S500
530 l/min. = (E530)
Start of opening
Opening pressure ... bar = ... [bar]
Secondary pressure relief
Pressure relief from B =
Pressure setting
Pressure setting ... bar at approx. 0.75 l/min. = ... [bar]
Ports X, L, E
(standard) with fittings in X and L (E=VSTI) = V
with fittings in X, L and E = R
Optional stroke−limiting
e.g. 1.2 mm of stroke−limiting (shims) = H12
Inlet port
port A = A
portA1 = A1
port2A = 2A
Option (consult Bucher Hydraulics)
external tank port, G
3
/4 = T
300−P−9050075−E−01/11.06
ESV
15/17
11 Flat design, sizes 16/20
11.1 Dimensions
d
cb
a
30
84
124
175
48
148
55.5
59.5
54.5
55.5
16
44
73.5
9088
189
66
max. 78
4141
68
61.5
69.5
35
39
98
37.5
210
5
35
59
MB
A
X
E
B
E
A
B
MB
ø1,0
L
X
A
E
B
L
R
max
10
0.01 / 100 mm
1
Fig. 5 Dimensions of ESV 16−B−F/ESV 20−B−F
300−4−10012911
1 Required quality of the mating surface
Design Ports
O−ring
Port B
A B E L X
ESV 16−B SAE 3/4" 6000psi SAE 3/4" 6000psi G 1/4" G 1/4" G 1/4" 3.53 x 24.99
ESV 20−B SAE 1" 6000psi SAE 1" 6000psi G 1/4" G 1/4" G 1/4" 5.53 x 32.92
Design Dimensions [mm]
a b c d
ESV 16−B M10 15.5 29.5 40.5
ESV 20−B M12 16 29 41
300−P−9050075−E−01/11.06
ESV
16/17
11.2 Performance graphs
∆p A to B = (Q)
Q [l/min]
pX [bar]
∆p B to A = (Q)
Q [l/min]
0 50 100 150 200 250 300 350
50
40
30
20
10
0
p [bar]
Pressure−relief valve, secondary PRV, Q = (Load)
(Example curve)
500
450
400
350
300
250
200
150
100
50
0
pB [bar]
050
*
*
100 150 200
Q [l/min]
* pressure setting
Opening pilot press. X from B to A, Q = (pX) at 33 bar load
pX [bar]
Q [l/min]
24
22
20
18
15
14
12
10
8
6
4
0
0
0
0
0
0
25
37.5
50
62.5
72.5
100
50
75
100
125
145
200
75
112.5
150
187.5
217.5
300
100
150
200
250
290
400
S100
S150
S200
S250
S290
S300
300−P−9050075−E−01/11.06
ESV
17/17
11.3 Model code
ESV
−−−−−−−−−
−
B F SV
Nominal size
size 16 = 16
size 20 = 20
Version
B= B
Design
flat design = F
Seal material
Temperature range
Nitrile (standard) −20
o
C to +90
o
C= N
Nitrile (low temperature) −50
o
C to +80
o
C= T
Viton −20
o
C to +200
o
C= V
Mounting bolts
without mounting bolts = O
with surface−treated mounting bolts = D
Control spool
Q at approx. 33 bar p B A Size 16 Size 20
100 l/min. = S100 = S100
150 l/min. = S150 = S150
200 l/min. = S200 = S200
240 l/min. = S240 = S240
250 l/min. = S250 = S250
290 l/min. = S290
300 l/min. = S300
Start of opening
Opening pressure ... bar = ... [bar]
Secondary pressure relief
Pressure relief from B =
Pressure setting
Pressure setting ... bar at approx. 0.75 l/min. = ... [bar]
Optional stroke−limiting
e.g. 1.2 mm of stroke−limiting (shims) = H12
Optional ports
accumulator port G
1
/4 = S
tank port G
3
/4 = T
Option
mechanical air−bleeding = E
E 2006 by Bucher Hydraulics AG, CH−6345 Neuheim.
www.bucherhydraulics.cominfo.nh@bucherhydraulics.com
All rights reserved.
Data is provided for the purpose of product description only, and must not be considered as warranted characteristics in the legal sense.
The information does not relieve users from the duty of conducting their own evaluations and tests. Because the products are subject to
continual improvement, we reserve the right to amend the product specifications contained in this catalogue.
